Fenestration is used to frame and mount glazing in the windows and entrance ways of buildings.
Traditionally, wooden fenestration has been employed for such purposes. Wooden fenestration functions effectively to provide both an aesthetically attractive window or doorway and also performs well as a thermal insulator.
Thermal insulation is important in fenestration to ensure that the temperature at the exterior of a building is not transferred into its interior.
The use of thermally insulative materials such as wood ensures that heat loss from the interior of a building is minimised in cold climates, and the interior of a building is not heated in warm climates.
It is also important to provide thermally insulating materials in fenestration to ensure moisture condensate is not formed on the interior surfaces of the fenestration.
If the interior faces of fenestration are cooler than the ambient temperature inside a building, this can cause moisture to condense and potentially damage adjacent components in the interior of a building.
However, wooden fenestration is not directly suited to mass production techniques and applications. Wood generally requires a high level of skill from a manufacturing labourer to section the required fenestration shapes and also to install the resulting fenestration in a building. Furthermore, the wood used, although relatively attractive in its final finished section, is also a relatively costly building material.
Aluminium fenestration has been developed as an alternative to wooden fenestration. Aluminium can be extruded into relatively complex profiles (or sections) in large volumes with relatively low labour costs.
Furthermore, the costs of the aluminium material are lower than that of wood, thereby resulting in a comparatively low cost fenestration product.
However, there are some existing problems present with the use of aluminium fenestration.
Aluminium fenestration does not have the same level of aesthetic appeal to some consumers, who have a preference for the more natural or warmer appearance of wood. Regulations regarding preservation of heritage buildings may also require that the aesthetics of wood are used in the interior of a building.
Aluminium also does not function effectively as a thermal insulator, which results in heat losses to the exterior of a building in cold climates and the reverse effect in hot climates.
Furthermore, condensate will also generally form on the exposed interior surfaces of the fenestration which can cause water or moisture damage to the surrounds of the window or doorway involved.
Some existing attempts have been developed to produce hybrid (or composite) fenestration systems which harness both the thermal and aesthetic advantages of wood and the manufacturing and cost advantages of aluminium fenestration. An example of composite fenestration is Fletcher Aluminium ALTI® system marketed in New Zealand as also detailed at the internet address, www.altinz.co.nz.
The ALTI® system is implemented as sliding panel fenestration. Sliding panel fenestration normally employs a fixed static panel and a sliding panel adjacent to the fixed panel. The sliding panel can be moved laterally across a track laid in the fenestration to open and close a window or doorway formed in a structure.
However, the ALTI® fenestration system also has a number of problems in its implementation.
A significant amount of wood is still required to clad the interior surfaces of the fenestration. In such instances the exposed interior face of the sliding panel provided is preferably clad with wood.
This again requires a reasonably skilled labour force to produce the wooden cladding required and also once again results in increased labour manufacturing cost for the resulting composite fenestration.
Furthermore, the amount of wood used again inflates the materials cost of the resulting fenestration.
Another type of fenestration system commonly used is the double hung window or ‘sash’ window. These types of windows incorporate two sliding panels or panes located with a paired set of tracks with one panel vertical disposed above the other when the window is closed. In the closed configuration the upper panel is disposed within the upper regions of a track on the exterior side of the fenestration facing outwards towards the exterior of a structure. The remaining panel is located within the lower portions of a track on the interior side of the fenestration to face towards the interior side of the structure involved. Some overlap is also provided between the lower regions of the upper “external” panel and the upper regions of the “internal” panel to prevent water leaking into the structure from the exterior side.
These double hung window fenestration assemblies allow both the exterior and interior panels to move within a set of vertically orientated tracks. However, as can be appreciated by those skilled in the art, a large section of the interior panel's track will be exposed to the interior of a structure when the panel is shut. This is aesthetically displeasing.
This aspect of the double hung window design has generally led to the implementation of this type of fenestration in thermally insulative materials. The thermally insulative properties of these materials are harnessed to prevent heat transfers across the fenestration assembly and in particular through the exposed surfaces to the interior of the building. For these reasons aluminium is generally considered an unsuitable material for double hung fenestration systems.
An improved fenestration system which addressed any or all of the above problems would be of advantage. Specifically a fenestration system which could be produced at relatively low cost and which had improved thermal efficiencies over the prior art would be an advantage. A fenestration system which has improved aesthetic appeal and which covered an interior track which may otherwise be exposed would also be of an advantage. Further an improved fenestration system or assembly which covered the track of an interior panel when the panel is in a closed position would also be of advantage.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents section part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.